#!/usr/bin/env node

const {Readable} = require('stream');
const rs=new Readable();
let c = 'a'.charCodeAt(0);
//==
//const Readable = require('stream').Readable;
rs._read = () =>{
  rs.push(String.fromCharCode(c++));
  if(c==='z'charCodeAt(0)+1)rs.push(null);
}
rs.pipe(process.stdout);
